▲ The earthquake struck Pohang, and the outer wall of the building was torn down.

On November 15th, 2017, at 2:29 p.m., an earthquake struck Pohang. The magnitude of this earthquake is 5.4, and it is the second strongest recorded earthquake in South Korea. By the way, compared to the earthquake in Gyeongju last year, the magnitude of the earthquake in Pohang is lower, but there were more people felt the stronger tremor, and there were more damages than the earthquake struck in Gyeongju. What is the reason why that happened?

To begin with, earthquakes happen at the place where the plates of crust collide or become far away with each other underground. We say that place is the hypocenter. Also, we say the point that meets the surface of the earth vertically is the epicenter. In South Korea, earthquakes whose magnitude are 5.0 or over 5.0 have occurred four times from 2016 to 2018. Especially, when the third and forth earthquakes occurred, there are many people who felt stronger tremor, and some damages are seen around each epicenter because of those earthquakes' high magnitudes. The third earthquake struck in Gyeongju, and its magnitude was 5.8. Moreover, the fourth earthquake struck in Pohang, and its magnitude was 5.4.

Many people who live in other areas revealed that when the earthquake struck Gyeongju, they could not feel any tremor. However, now, they felt some tremor in Pohang. However, this earthquake's magnitude was lower than the last earthquake in Gyeongju. So, many people were curious about that. In response to that, experts inferred that this case is because of the difference of the hypocenters' depth of both earthquakes. One of them, an earthquake professional Cho Eun-young said, "Generally speaking if the hypocenter of the earthquake is shallow, the tremor is stronger. Also, last earthquake's hypocenter was beneath 12~13km from the surface of the earth, but this earthquake's hypocenter is beneath around 6.9km from the surface of the earth. So, more people would feel the tremor definitely. " Like that, we could know that this case was because of the different depth of both earthquake's hypocenters.

Pohang's earthquake's magnitude was lower than the last earthquake in Gyeongju, but this was "shallow earthquake", so there were stronger tremors at the surface of the earth. Plus, the government is trying to help people who were affected by this earthquake in Pohang.